Many circuits, such as sampled data circuits, require or utilize accurate charges in the processing of sampled data. Charge sources are used to provide these accurate charges. Conventionally, at least one capacitor is used directly for each charge source. That is, if one charge source is needed at least one capacitor is charged up and then discharged as needed to directly provide the charge. Likewise, if n charge sources are needed (where n is 1 or greater than 1) at least n capacitors are used to provide the n charge sources. In some implementations, a single charge source may be composed of more than a single capacitor. For example, a bank of capacitors may be used in a manner that allows the bank to produce a selectable amount of charge to be provided directly, through discharge of the bank, to a circuit that requires the charge. When the number of charge sources is great, such as in an integrated circuit or electronic system that includes multiple sampled data circuits, the number of capacitors required to provide the charge sources can be quite large when it is considered that there is at least a one-to-one relationship between the number of capacitors and charge sources and often that ratio is greater than one capacitor per charge source. In many instances charge sources and data sampling circuits which utilize charge sources may be included in an input device that is used to receive user input.
Input devices including proximity sensor devices (also commonly called touchpads or touch sensor devices) are widely used in a variety of electronic systems. A proximity sensor device typically includes a sensing region, often demarked by a surface, in which the proximity sensor device determines the presence, location and/or motion of one or more input objects. Proximity sensor devices may be used to provide interfaces for the electronic system. For example, proximity sensor devices are often used as input devices for larger computing systems (such as opaque touchpads integrated in, or peripheral to, notebook or desktop computers). Proximity sensor devices are also often used in smaller computing systems (such as touch screens integrated in cellular phones and tablet computers). Such touch screen input devices are typically superimposed upon or otherwise collocated with a display of the electronic system.